US 4,810,356 AGrant
Process for Treating Gas Oils
Issue Date:1989-03-07
•20 Claims
Abstract
A process for the treatment of a gas oil fraction to produce a lighter fraction useful as diesel fuel and/or gasoline comprising subjecting the gas oil fraction to dewaxing and mild hydracracking treatments. The dewaxing is carried out over a silicalite dewaxing catalyst. The dewaxing and mild hydrocracking treatments may be carried out sequentially or simultaneously. The gas oil feed may be passed successively through a silicalit-catalyst bed, a bed of hydrotreating catalyst and a bed of hydrocracking catalyst.
Metadata
Assignee
- Labofina, S.A.
Inventors
- Jacques F. Grootjans
- Pierre J. Bredael
Application Information
Application Number:US 0102237
Filing Date:1987-02-03
Priority Date:1986-02-03
Art Unit:116
Classifications
IPC:
C10G 6500
Field of Search:
20859;111
Patent Drawings
This patent does not have any drawings.
Description
Example 1
The employed catalysts were silicalite (available from Union Carbide and having mean pore size of about 0.55 nm and crystallite size of less than 8 um) and a catalyst comprising Ni and Mo on Al.sub.2 O.sub.3 /SiO.sub.2 and having the following characteristics:
specific area: 153 m.sup.2 /g
pore volume: 0.53 ml/g
NiO: 3.6 weight %
MoO.sub.3 : 19.6 weight %
This latter catalyst was pretreated by subjecting it to a drying step at 130.degree. C. and then to a sulfuration treatment at 54 bars with a mixture H.sub.2 +H.sub.2 S (1.1 vol. %), first at 250.degree. C. up to a partial pressure of H.sub.2.sup.S higher than 0.03 bar at the reactor exit, and then progressively up to 320.degree. C., while keeping the partial pressure of H.sub.2.sup.S higher than 0.03 bar at the exit. The sulfided Ni-Mo catalyst contained about 10 weight % of sulfur.
A reactor having an inner diameter of 2.5 cm was charged with 20 vol. % of silicalite (height: 7 cm) and 80 vol. % (height: 28 cm) of sulfided Ni-Mo catalyst, both being disposed between two layers of inert material (height of each layer: 40 cm).
A hydrocarbon feed was passed through the reactor, this feed passing successively through the silicalite bed and the Ni-Mo catalyst bed.
This feed was a gas oil from a vacuum distillation unit having the following characteristics:
fraction up to 180.degree. C.: 0.1 wt %
fraction 180.degree. C.-250.degree. C.: 2.55 wt %
fraction 250.degree. C.-370.degree. C.: 18.39 wt %
fraction 370.degree.-500.degree. C.: 64.55 wt %
fraction 500.degree. C.+.degree.C.: 14.41 wt %
specific gravity d.sub.15/4 : 0.91
sulfur content: 1.42 wt %
total nitrogen: 1010 ppm.
basic nitrogen: 267 ppm.
A hydrogen stream from a refinery (containing about 85% H.sub.2) was passed through the reactor at a H.sub.2 partial pressure of at least 40 bars, simultaneously with the feed.
The run was carried out at 405.degree. C. and a pressure of 54 bars. The other working conditions and the conversion rates (weight percentage of the 370+.degree. C. fraction which has been converted) are given in the following Table 1. The ratio of recycled gas/hydrocarbons was varied as a function of the LHSV of the feed in order to keep constant the flow rate of recycled gas.
Example 2
The procedure of Example 1 was repeated, but by replacing one half of the Ni-Mo catalyst with a Co-Mo alumina catalyst (commercially available as Ketjen 742). The feed was passed successively on the silicalite, the Co-Mo catalyst and the Ni-Mo catalyst beds.
The conversion yield was 48.7% with a LHSV of 0.6.
Example 3
The procedure of Example 1 was repeated, but by inverting the catalysts, the feed passing first over the Ni-Mo catalyst and then the silicalite bed.
The results are given in Table 2.
By comparison with run 1B, it can be shown that the properties of the diesel fuel fractions are better.
Comparative experiments (hereinafter runs C1 to C9) were carried out in order to evaluate the synergistic effect resulting from the use of the process of this invention. To this end, catalysts given in the following Table 3 were tested and the conversion yields were compared with those obtained in the hereinabove described Examples.
These comparative runs clearly show that a synergistic effect results from the combination of a dewaxing treatment and a mild hydrocracking treatment. For instance, the data of run 3A make it possible to calculate the conversion rate resulting from the mild hydrocracking step, taking into account the conversion rate reached in run C1 for silicalite alone, as follows: ##EQU1## This result with the conversion rates of 34.9 and 26.9% obtained with runs C2 and C3 respectively.
The composition of some effluents and the properties of some fractions are given in Table 4, where they are compared with those of run 1A.
Example 4
A gas oil feed comprising:
fraction 370+.degree. C.: 78.1 wt %
fraction 250.degree. C.-370.degree. C.: 19.1 wt %
fraction 180.degree. C.-250.degree. C.: 2.8 wt %
was treated according to the process of this invention and this treatment was followed by a usual fluid catalytic cracking at 510.degree. C., 1.7 bar and LHSV=40 on zeolite.
The recovered effluent contained (wt %)
10.6%: gas (mainly C.sub.3 and C.sub.4)
35.8%: gasoline (fraction C.sub.5 -180.degree. C.)
10.0%: kerosene (fraction 180.degree. C.-250.degree. C.)
32.1%: diesel fuel (fraction 250.degree. C.-370.degree. C.)
7.1%: light cycle oil
2.7%: residue
By way of comparison, a feed having the same composition was subjected to a mild hydrocracking and then to a catalytic cracking under the same working conditions. The effluent contained (wt %):
8.6%: gas (mainly C.sub.1 -C.sub.3)
38.5%: gasoline
8.5%: kerosene
30.4%: diesel fuel
9.5%: light cycle oil
3.4%: residue
This example shows that more kerosene and diesel fuel are produced with the process of this invention. Furthermore, the recovered gases are more valuable.
Having described specific embodiments of the present invention, it will be understood that modification thereof may be suggested to those skilled in the art, and it is intended to cover all such modifications as fall within the scope of the appended claims.
Claims
We claim:
1. A process for the treatment of a hydrocarbon feed containing at least 1 wt.% sulfur having a distillation curve within the range of heavy gas oils comprising subjecting said hydrocarbon feed to a mild hydrocracking treatment and a dewaxing treatment to recover a product of reduced boiling point range having an increased amount of light hydrocarbons wherein: (a) said dewaxing treatment is conducted over an unmodified crystalline silica polymorph silicalite dewaxing catalyst under temperature and pressure conditions sufficient to crack waxy paraffinic hydrocarbons in said feedstock; (b) said mild hydrocracking treatment is carried out over a hydrocracking catalyst at temperature and pressure conditions to produce hydrocarbons of a reduced boiling point range; and (c) said silicalite dewaxing catalyst is present in an amount within the range of 15-25 volume % of the total catalysts employed in said process.
2. The method of claim 1 wherein said dewaxing and mild hydrocracking treatments are carried out simultaneously over a blend comprising a discrete physical mixture of said silicalite dewaxing catalyst and said hydrocracking catalyst.
3. A process for the treatment of a hydrocarbon feed containing at least 1 wt.% sulfur having a distillation curve within the range of heavy gas oils comprising subjecting said hydrocarbon feed to a mild hydrocracking treatment and a dewaxing treatment to recover a product of reduced boiling point range having an increased amount of light hydrocarbons wherein: (a) said dewaxing treatment is conducted over an unmodified crystalline silica polymorph silicalite dewaxing catalyst under temperature and pressure conditions sufficient to crack waxy paraffinic hydrocarbons in said feedstock; (b) said mild hydrocracking treatment is carried out over a hydrocracking catalyst at temperature and pressure conditions to produce hydrocarbons of a reduced boiling point range; (c) said silicalite dewaxing catalyst is present in an amount within the range of 15-25 volume % of the total catalysts employed in said process; and (d) said dewaxing treatment and said mild hydrocracking treatment are carried out sequentially.
4. The method of claim 3 wherein said mild hydrocracking treatment is carried out initially and the effluent from said mild hydrocracking treatment is passed to said silicalite dewaxing catalyst to carry out said dewaxing treatment.
5. The method of claim 3 wherein said dewaxing treatment is carried out initially and the effluent from said dewaxing treatment is passed over said hydrocracking catalyst to implement said mild hydrocracking treatment.
6. The method of claim 5 further comprising an intermediate hydrotreating treatment between said dewaxing and said mild hydrocracking treatments wherein the effluent from said dewaxing treatment to remove sulfur therefrom is passed over a hydrotreating catalyst then the effluent from said intermediate hydrotreating treatment is passed to said mild hydrocracking treatment.
7. The process of claim 1 wherein the feed contains at least 75% of hydrocarbons having a boiling point within the range of 370.degree. C.-540.degree. C.
8. The process of claim 1 wherein said process is carried out at a temperature of 350.degree. C.-450.degree. C., a pressure of 1-80 bars, a LHSV of 0.1-20 hr.sup.-1 and in the presence of hydrogen in such an amount that the volume ratio H.sub.2 /hydrocarbons is between 50-5000 standard liters per liter.
9. The process of claim 8 wherein said process is carried out at a temperature of 380.degree. C.-420.degree. C., a pressure of 35-65 bars, a LHSV of 0.5-5, and in the presence of hydrogen in such an amount that the volume rate H.sub.2 /hydrocarbons is between 250-1000 standard liters per liter.
10. The process of claim 3 wherein the steps (a) and (b) are carried out by passing the feed successively on separated beds of catalysts in the same reactor.
11. A method for the conversion of a hydrocarbon feedstock boiling in the gas oil range to produce a fraction of reduced boiling point range and reduced pour point, comprising: (a) passing a hydrocarbon feedstock containing at least 1 wt.% sulfur and having a final boiling point in excess of 450.degree. C. and a 25 wt.% boiling point in excess of 370.degree. C. into a reaction zone and within said reaction zone dewaxing said fraction over an unmodified silicalite dewaxing catalyst under temperature and pressure conditions sufficient to crack waxy paraffinic hydrocarbons in said feedstock; (b) passing the dewaxed hydrocarbon fraction from said reaction zone into a subsequent reaction zone and within said subsequent reaction zone catalytically hydrocracking said fraction in the presence of a hydrocracking catalyst under mild operating conditions including a temperature within the range of 350.degree. C.-450.degree. C. and a pressure within the range of atmospheric pressure to 80 bars to produce a product of reduced boiling point range which is predominantly in the diesel oil range or below; and (c) withdrawing product from said subsequent reaction zone.
12. The method of claim 11 wherein step (a) is carried out at a temperature within the range of 350.degree. C.-450.degree. C. and a pressure within the range of atmospheric pressure to 80 bars.
13. The method of claim 11 further comprising an intermediate hydrotreating treatment between steps (a) and (b) wherein the dewaxed hydrocarbon fraction from step (a) is passed into an intermediate reaction zone and within said intermediate reaction zone catalytically hydrotreating said hydrocarbon fraction in the presence of a hydrotreating catalyst to remove sulfur therefrom.
14. The method of claim 13 wherein said silicalite dewaxing catalyst is present in an amount within the range of 15-25 volume % and the composite of said hydrocracking and hydrotreating catalyst is present within the range of 75-85 volume % of the total of said silicalite and said hydrocracking and hydrotreating catalysts.
15. The method of claim 13 wherein said initial, intermediate and subsequent reaction zones are defined by respective layers of catalysts within the same reactor.
16. The method of claim 15 wherein said reactor is operated in a downflow mode in which the hydrocarbon feed trickles in a liquid phase downward through the successive layers of silicalite, hydrotreating catalyst and hydrocracking catalyst.
17. The method of claim 11 wherein said hydrocracking catalyst comprises a mixture of Group VIB and Group VIII metal components.
18. The method of claim 13 wherein the hydrotreating catalyst in said intermediate reaction zone comprises cobalt and molybdenum components and the hydrocracking catalyst in said subsequent reaction zone comprises nickel and molybdenum components.
19. The method of claim 18 wherein said hydrocarbon fraction is passed over said catalyst at a space velocity (LHSV) within the range of 0.5-5 hr.sup.-1.
20. The method of claim 13 wherein the contact time of the composite of said hydrotreating and hydrocracking catalysts is greater than the contact time of said feed over said silicalite dewaxing catalyst.
Patent Citations (20)
| Patent | Date | Inventor | Cited By |
|---|---|---|---|
| US3700585 | 1972-10-01 | Chen et al. | |
| US4061724 | 1977-12-01 | Grose | |
| US4229282 | 1980-10-01 | Peters et al. | |
| US4292166 | 1981-09-01 | Ceorring et al. | |
| US4347121 | 1982-08-01 | Mayer et al. | |
| US4361477 | 1982-11-01 | Miller | |
| US4362653 | 1982-12-01 | Robinson | |
| US4394249 | 1983-07-01 | Shen | |
| US4428825 | 1984-01-01 | Ward et al. | |
| US4428862 | 1984-01-01 | Ward et al. | |
| US4443329 | 1984-04-01 | Eberly, Jr. et al. | |
| US4458024 | 1984-07-01 | Oleck et al. | |
| US4490570 | 1984-12-01 | Forward et al. | |
| US4548705 | 1985-10-01 | Young et al. | |
| US4561967 | 1985-12-01 | Miller | |
| US4597854 | 1986-07-01 | Penick | |
| US4599473 | 1986-07-01 | Debras et al. | |
| US4648958 | 1987-03-01 | Ward | |
| EPX43681 | 1984-08-01 | ||
| EPX72220 | 1986-04-01 |